Trimming blade holding device



June 7, 1966 R. H. MIcHAUD 3,254,617

TRIMMING BLADE HOLDING DEVICE Filed May 14, 1964 2 sheets-sheet 1 R. H. MICHAUD 3,254,617

TRIMMING BLADE HOLDING DEVICE June 7, 1966 Filed May 14, 1964 2 Sheets-Sheet 2 United States Patent 3,254,617 TRIMMING BLADE HOLDING DEVICE Robert Henry Michaud, 303 Belair St., New Bedford, Mass. Filed May 14, 1964, Ser. No. 367,304 2 Claims. (Cl. 112-126) This invention relates to'improvements in the mechanism of a Merrow sewing machine, model No. M3DW3. Two pieces of fabric can be joined together by overlock stitching performed on the improved machine to produce a stronger seam than results from the use of the standard machine. This is done by folding or curling the margin of the fabric pieces where the overlock stitches are being formed so that the machine needle pierces the pieces of fabric along a line relatively remote from the edge but with the formation of a relatively narrow seam. This is especially advantageous when joining pieces of cloth such as flannel which ravels readily when sewn near the edge and easily comes apart under tension.

Reference is made to the drawings, of which FIGUREI is a perspective View, on an enlarged scale, of mechanism embodying the invention;

FIGURE 2 is a plan view of a piece of cloth indicating the effect of the successive operations by said mechanism thereon;

FIGURE 3 is an exploded perspective view of a presser foot and folder assembly;

FIGURE 4 is a perspective view of a standard throat plate which has been altered according to the invention;

FIGURE 5 is a perspective view of a spacer to elevate the throat plate;

FIGURE 6 is a fragmentary perspective view of a sewing machine block on which the throat plate is secured;

FIGURE 7 is a fragmentary perspective view of an upper cutter carrier;

FIGURE 8 is an exploded perspective view of an upper cutter holding block;

FIGURE 9 is a perspective view of a waste guard;

'FIGURE 10 is a perspective view of a lower cutter; and

FIGURE 11 is a perspective view of an upper cutter.

In FIGURE 1 is illustrated part of a standard block 20 of a Merrow overlock sewing machine. Mounted on the block is a throat plate 22 which is raised slightly above its customary position on the block by a spacer 24 which underlies a portion of it. As indicated in FIGURE 4, the right hand edge of the throat plate is reshaped to form a reverse curve as at 26 which merges with a side of the stitching tongue 28, this tongue being an integral part of the throat plate 22.

A presser foot 30 is over the throat plate and is adapted to press thereon when the machine is in operation. A folder 32 is adjustably secured to the presser foot by a screw 34 which passes through a slot 36 in an extension 38 thereof which fits in a transverse channel 40 in the presser foot. Thefolder can be adjusted to the right or left to increase or diminish the clearance between it and the throat plate. When the presser foot is in operative position, the folder 32 is alongside the stitching tongue 28, as indicated in FIGURE 1, where it effectively curls the margin of the fabric advancing over the throat'plate under the edge 26 of the throat plate and around the stitching tongue 28. The loopers (not shown) which customarily form the overlock stitches about the tongue 28 thus form their stitches about the marginal portion of the fabric as well, the margin being curled down around the tongue 28. The purpose of elevating the throat plate 22 by the use of a spacer 24 is to prevent the lower looper (not shown) from catching on the edge of the fabric where it extends down slightly below the tongue 28.

3,254,617 Patented June 7, 1966 ice For the production of a satisfactory seam, it is important that the margin of the fabric approaching the folder 32 be uniform. To ensure this, cutters are provided to trim the margin just before it reaches the folder. For this purpose, a lower'cutter blade 40 is mounted at the side of the block 20 just forward of the reversely curved edge 26 of the throat plate 22. An upper cutter blade 42 is mounted for vertical reciprocation above the blade 40 to cooperate therewith in making rapid shearing cuts to trim the edge of the fabric. The upper blade 42 is secured in a, holding block 44 which in turn is adjustably secured to a carrier 46. This carrier'is a standard part of a Merrow machine and a' horizontal portion thereof having a dovetail groove is shown in FIGURES 1 and 7.

The blade holding block 44 is adjustably secured to the carrier 46 by a dovetail tenon 47 fitting in the groove in the carrier, a headless setscrew 48 being employed to lock the block in adjusted position. The block 44 has a slot 50 from top to bottom extending parallel to the dovetail edge from one side of the block nearly to the other side, this slot forming a transverse jaw 52 at the forward end 'of the block. A horizontal hole 54 large enough for the setscrew 48 to slide through is provided through the jaw 52 to the slot 50 and a reduced, screwthreaded continuation of this hole extends to the dovetail edge of the block. To lock the block to the carrier 46,

the headless setscrew 48 is pushed through the hole 54 into threaded engagement with the continuation of the hole and is then rotated until its leading end bears against the bottom of the dovetail groove of the carrier 46. When this has been done, a second screw 56 with a thread similar to that of the screw 48, and a head 58 is thrust through the hole 54 and then rotated until' the head 58 bears against the side of the jaw 52, that is, the front end of the block. Further rotation of the screw 56 will draw the free end of the jaw 52 toward the body of the block 44. The jaw 52 and the body of the block have opposed recesses 60, 62 in the form of vertical grooves to receive the side edges 64, 66, respectively, of the upper cutter blade 42. When the blade 42 is in properly adjusted position, the screw 56 isrotated to press the jaw toward the body of the block so as to :bind the.blade tightly in position. Vertical reciprocation of the blade 42 results in shearing cuts between" its edge 68 and the edge 70 of the lower blade 40. In order not to interfere with the folder 32, the cutters are located about A inch forward of the usual location on the Merrow machine. For this purpose the portion of the blade 40 having the cutting edge 70 is offset forward so that the customary bladegripping clamps '72, 74 of the Merrow machine can be' employed without change. The corresponding forward shift of the .upper blade 42 is achieved by mounting it on a block 44 of suitable length. 7

When the fabric is trimmed by the cutter blades 40, 42, it is desirable that the trimmings be kept from getting tangled in the folder 32 or the loopers. For this purpose a waste guard 76 is mounted in the slot 50 of'the block 44 so as to project down alongside of the cutter blades 40, 42 in a plane at right angles to those of the blades. The waste guard is of spring steel and is transversely curved so that when in the slot its edges press against one side wall and its vertical median presses against the other side wall of the slot, thus avoiding looseness in the slot. The screw 56 passes through a hole 78 in the waste guard to retain it in place. In FIGURE 1 the lower portion of the waste guard is broken away so as to show the parts behind it.

The results'of successive operations on a piece of fabric 80 are illustrated in FIGURE 2. The cutters trim the fabricv at 82, forming a strip of waste 84 which is discarded. As the trimmed edge advances beyond the cutters, the margin curls under as it slides over the reversely curved portion of the edge of the throat plate. The overlook stitches 86 are then formed about the portion of the fabric which enfolds the stitching tongue just before passing beyond the tongue.

I claim:

1. In an overlock sewing machine having a horizontally disposed vertically reciprocable carrier, an elongated blade-holding block adjustably secured to said carrier and projecting forward therefrom, an upper cutter blade gripped by said block and projecting vertically downward therefrom, a lower cutter blade below said upper blade, means supporting said lower blade in shearing relation to said upper blade, said carrier having a dovetail groove therein, said block having at one end thereof a dovetail edge slidably fitted in said groove, said block also having a transverse slot from top to bottom extending across from one side nearly to the other side thereof and parallel to the dovetail edge, said slot forming a transverse jaw remote from said dovetail edge, said block having a horizontal hole through said jaw to said slot and a reduced, screw-threaded continuation of said hole through to the dovetail edge, a headless setscrew in threaded engagement in said continuation and projecting from said dovetail edge thereof to press against the bottom of said groove whereby to lock the block in adjusted position relative to said carrier, said block having vertical grooves on each side of said slot to receive the side edges of the upper blade when disposed in a plane parallel to the sides of the block, and means for gripping said upper blade, said means including a screw extending through said hole and in threaded engagement with said continuation, said screw having a head bearing against said jaw to press said jaw toward the remainder of the block.

2. Mechanism as described in claim 1, a waste guard carried by said block adjacent to said upper blade, and means for supporting said waste guard in said slot to project down therefrom.

References Cited by the Examiner UNITED STATES PATENTS 846,065 3/1907 Stedman 1l2122 1,094,858 4/1914 Merrow 1l2151 X 1,717,050 6/1929 Maier 112 -260 2,017,382 10/1935 Washburn l12126 2,247,127 6/1941 Knaus 112122 FRANK J. COHEN, Primary Examiner.

JORDAN FRANKLIN, Examiner.

R. J. SCANLAN, Assistant Examiner. 

1. IN AN OVERLOCK SEWING MACHINE HAVING A HORIZONTALLY DISPOSED VERTICALLY RECIPROCABLE CARRIER, AN ELONGATED BLADE-HOLDING BLOCK ADJUSTABLY SECURED TO SAID CARRIER AND PROJECTING FORWARD THEREFROM, AN UPPER CUTTER BLADE GRIPPED BY SAID BLOCK AND PROJECTING VERTICALLY DOWNWARD THEREFROM, A LOWER CUTTER BLADE BELOW SAID UPPER BLADE, MEANS SUPPORTING SAID LOWER BLADE IN SHEARING RELATION TO SAID UPPER BLADE, SAID CARRIER HAVING A DOVETAIL GROOVE THEREIN, SAID BLOCK HAVING AT ONE END THEREOF A DOEVTAIL EDGE SLIDABLY FITTED IN SAID GROOVE, SAID BLOCK ALSO HAVING A TRANSVERSE SLOT FROM TOP TO BOTTOM EXTENDING ACROSS FROM ONE SIDE NEARLY TO THE OTHER SIDE THEREOF AND PARALLEL TO THE DOVETAIL EDGE, SAID SLOT FORMING A TRANSVERSE JAW REMOTE FROM SAID DOVETAIL EDGE, SAID BLOCK HAVING A HORIZONTAL HOLE THROUGH SAID JAW TO SAID SLOT AND A REDUCED, SCREW-THREADED CONTINUATION OF SAID HOLE THROUGH TO THE DOVETAIL EDGE, A HEADLESS SETSCREW IN THREADED ENGAGEMENT IN SAID CONTINUATION AND PROJECTING FROM SAID DOVETAIL EDGE THEREOF TO PRESS AGAINST THE BOTTOM OF SAID GROOVE WHEREBY TO LOCK THE BLOCK IN ADJUSTED POSITION RELATIVE TO SAID CARRIER, SAID BLOCK HAVING VERTICAL GROOVES ON EACH SIDE OF SAIDF SLOT TO RECEIVE THE SIDE EDGES OF THE UPPER BLADE WHEN DISPOSED IN A PLANE PARALLEL TO THE SIDES OF THE BLOCK, AND MEANS FOR GRIPPING SAID UPPER BLADE, SAID MEANS INCLUDING A SCREW EXTENDING THROUGH SAID HOLE AND IN THREADED EGAGEMENT WITH SAID CONTINUATION, SAID DCREW HAVING A HEAD BEARING AGAINST SAID JAW TO PRESS SAID JAW TOWARD THE REMAINDER OF THE BLOCK. 